基于容积脉搏波振幅梯度的血压检测法的研究

提出了基于容积脉搏波振幅梯度的血压检测方法,并开发了相应的检测系统,进行了原理测试和对比实验。首先,对三名实验者进行了验证性实验,确认了系统的稳定性;其次,以水银式血压检测法作为对比方法,进行了基于容积脉搏波振幅梯度的血压检测法的对比实验,实验结果表明两种血压检测法具有良好的直线相关性;最后,用Bland-Altman图进行分析,结果表明收缩压和舒张压均有94%以上的实验结果分布在95%置信区间的范围之内,说明两种测量方法具有良好的一致性。基于容积脉搏波振幅梯度的血压检测法与水银式血压检测法具有大致相同的检测精度,本研究提出的新的血压检测法对间歇式血压检测是有效的。     

微循环容积脉搏血流信号的频率特性分析

本文利用微循环模型来研究容积脉搏血流的频率响应特性 ,从伯德图中找到影响模型频率响应的两个特征参数 ,即阻尼比 ξ和转角频率ωn。通过分析这两个特征参数的数值及其变化 ,可以确认出微循环的不同优劣状态。实验结果证实了模型分析结果。     

微循环容积脉博血流信号的频率特性分析

本文利用微循环模型来研究容积脉博血流的频率响应特性,从伯德图中找到影响模型频率响应的两个特征参数,即阻尼比ξ和转角频率ωn。通过分析这两个特征参数的数值及其变化,可以确认出微循环的不同优劣状态。实验结果证实了模型分析结果。     

阻抗平衡式微血管血压检测系统的分析与研究

微循环血压检测技术是深入研究微循环所必须的。本文介绍一个以玻璃微插管为基础的实验系统,用以测量微循环血压。运用现代控制理论的方法,对系统作了分析;并对瞬态特性、静态特性等品质指标进行了测试。动物实验证明了系统方案的可行性。最后我们提出了用分布参数控制系统的分析方法对系统进行进一步分析,以期更完整地把握其动力学性质。     

基于掌上电脑的袖珍式血压Holter研制

介绍了一种基于掌上电脑的新型袖珍式血压Holter系统。采用低功耗单片机控制血压测量过程，配置与掌上电脑的接口，根据用户需要可通过掌电脑存储，显示，分析血压数据，可对测量参数进行控制修改，并实现数据的远程传输。该系统硬件部分由模拟电路的部分，智能单元部分，外设接口部分三大部分组成，分别给出了各部分结构和工作原理。软件部分主要介绍了血压数据的获取及Holter系统前端与掌上电脑的通信接口部分，该系统具有轻便，智能，操作方便，精度高，功耗低，性能稳定性的特点，有望成为家庭血压监护的理想仪器。     

家庭心电/血压监护网中血压分析功能的设计与实现

在家庭心电／血压监护网中,血压分析功能是该系统的重要组成部分,根据血压的特点和意义,作者设计了一种通过图形式方显示血压数值的方法,为医务人员的诊断提供了方便。该软件包括两部分：２４小血压变化趋势图和月血压变化趋势图。     

一种新型爬楼梯轮椅的动力学建模及稳定性分析

本文介绍了一种新型爬楼梯轮椅在正常运动状态中翻转状态的动力学建模方法,基于此模型,对爬楼梯轮椅的运动特性进行了计算机仿真。为了进行爬楼梯轮椅的稳定性分析,文章中引入了基于能量考虑的阻翻能量裕量的概念来表征爬楼梯轮椅的翻转特性。其后,分析了爬楼梯轮椅曲柄平均角速度的改变对其稳定性的影响。仿真结果显示,阻翻能量裕量随着曲柄角位移的不同而改变,曲柄平均角速度的改变对其稳定性具有明显的影响。     

血压监测和时间生物学测量用于鉴别原发性和继发性高血压

问题是:“血压监测是否可以用来鉴别原发性和继发性高血压呢?”这是当前研究所面临的一个难题。我们对108名原发性高血压病人和32名继发性高血压的病人,施行了血压监测。用单余弦图分析时序数据,并用多变量鉴别分析法处理节律测量特征。     

闭环在线检测自动反馈控制系统医学模型研究

目的:抢救病人有一个给药量及速度问题,病人对药物反应反馈到医生或计算机分析系统,后者(控制器)做出调整用药及给药速率的决定与指令,从而获得最好治疗效果。原理:人体血压调节是一个具有负反馈的闭环控制系统,特点是系统被控对象的输出(被控制量)会反送回来影响调节器的输出,形成一个或多个闭环。这里调节器的传递函数采用PID。则函数方程为AS=KSt/t τ。结果与讨论:实际中采用应用最为广泛的调节器控制规律为比例、积分、微分控制,简称PID调节。其结构简单、稳定性好、工作可靠、按以上理论设计的仪器动物试验中发现该系统从获取血压变化到多次反馈调整给药整个周期短、计算准确,疗效可靠为临床争取了时间,是一个很有发展前景的抢救危重病人的系统。     

一种血压反馈控制系统的状态分析方法

通常在判断血压状态时,先划一个界限,然后将实际血压与这个界限作比较,以此来判断血压状态。这样的判断强调了血压的现值,而没有将血压变化率的信息展现出来。提出血压状态分析法,包括血压状态图和血压稳定性。以家兔为对象、去甲肾上腺素为扰动剂,采集动物在给药前血压平稳期、药物起效期、快速上升期、剧烈振荡期、血压恢复期和给药后血压平稳期的血压数据,建立血压反馈控制系统数学模型结构和血压状态图。根据采集的血压数据,分析血压状态图中血压的稳定态和稳定域、血压变化率的稳定域。通过动物实验,对这种血压状态分析法进行检验,为进一步研究血压控制技术提供新理论和新方法。     

Causal relationship between heart rate and arterial blood pressure variability signals

A method is described which allows the determination of the causal relationship existing between two biological signals (heart rate and arterial blood pressure variability signals) which carry information about the role of control elicited by the autonomic nervous system. This method assumes an autoregressive (AR) model for the two signals to check the cross-correlation of the two residuals after AR identification. This information, together with the classical parameters of the spectral analysis (mean, variance, frequency and power in two typical bands, gain, phase and coherence) may provide a more precise evaluation of the complex mechanisms involved in the control of heart rate and blood pressure in numerous physiopathological situations.     

Stability limits modulate whole-body motor learning

Our daily movements exert forces upon the environment and also upon our own bodies. To control for these forces, movements performed while standing are usually preceded by anticipatory postural adjustments (APAs). This strategy is effective at compensating for an expected perturbation, as it reduces the need to compensate for the perturbation in a reactive manner. However, it can also be risky if one anticipates the incorrect perturbation, which could result in movements outside stability limits and a loss of balance. Here, we examine whether the margin for error defined by these stability limits affects the amount of anticipation. Specifically, will one rely more on anticipation when the margin for error is lower? Will the degree of anticipation scale with the margin for error? We took advantage of the asymmetric stability limits (and margins for error) present in the sagittal plane during upright stance and investigated the effect of perturbation direction on the magnitude of APAs. We also compared anticipatory postural control with the anticipatory control observed at the arm. Standing subjects made reaching movements to multiple targets while grasping the handle of a robot arm. They experienced forward or backward perturbing forces depending on the target direction. Subjects learned to anticipate the forces and generated APAs. Although subjects had the biomechanical capacity to adapt similarly in the forward and backward directions, APAs were reduced significantly in the backward direction, which had smaller stability limits and a smaller margin for error. Interestingly, anticipatory control produced at the arm, where stability limits are not as relevant, was not affected by perturbation direction. These results suggest that stability limits modulate anticipatory control, and reduced stability limits lead to a reduction in anticipatory postural control.     

Dynamic stability control in forward falls: postural corrections after muscle fatigue in young and older adults

Many studies report that muscle strength loss may alter the human system’s capacity to generate rapid force for balance corrections after perturbations, leading to deficient recovery behaviours. Yet little is known regarding the effect of modifications in the neuromuscular system induced by fatigue on dynamic stability control during postural perturbations. This study investigates the effect of muscle strength decline induced by fatiguing contractions on the dynamic stability control of young and older adults during forward falls. Eleven young and eleven older male adults had to regain balance after sudden falls before and after submaximal fatiguing knee extension–flexion contractions. Young subjects had a higher margin of stability than older ones before and after the fatiguing task. This reflects their enhanced ability in using mechanisms for maintaining dynamic stability (i.e. a greater base of support). The margin of stability, the boundary of the base of support and the position of the extrapolated centre of mass, remained unaffected by the reduction in muscle strength induced by the fatiguing contractions, indicating an appropriate adjustment of the motor commands to compensate the deficit in muscle strength. Both young and older adults were able to counteract the decreased horizontal ground reaction forces after the fatiguing task by flexing their knee to a greater extent, leading to similar decreases in the horizontal velocity of centre of mass as in the pre fatigue condition. The results demonstrate the ability of the central nervous system to rapidly modify the execution of postural corrections including mechanisms for maintaining dynamic stability.     

Adaptive feedback analysis and control of programmable stimuli for assessment of cerebrovascular function

The assessment of cerebrovascular regulatory mechanisms often requires flexibly controlled and precisely timed changes in arterial blood pressure (ABP) and/or inspired CO₂. In this study, a new system for inducing variations in mean ABP was designed, implemented and tested using programmable sequences and programmable controls to induce pressure changes through bilateral thigh cuffs. The system is also integrated with a computer-controlled switch to select air or a CO₂/air mixture to be provided via a face mask. Adaptive feedback control of a pressure generator was required to meet stringent specifications for fast changes, and accuracy in timing and pressure levels applied by the thigh cuffs. The implemented system consists of a PC-based signal analysis/control unit, a pressure control unit and a CO₂/air control unit. Initial evaluations were carried out to compare the cuff pressure control performances between adaptive and non-adaptive control configurations. Results show that the adaptive control method can reduce the mean error in sustaining target pressure by 99.57 % and reduce the transient time in pressure increases by 45.21 %. The system has proven a highly effective tool in ongoing research on brain blood flow control.     

Autonomic dysregulation in ob/ob mice is improved by inhibition of angiotensin-converting enzyme

The leptin-deficient ob/ob mice are insulin resistant and obese. However, the control of blood pressure in this model is not well defined. The goal of this study was to evaluate the role of leptin and of the renin-angiotensin system in the cardiovascular abnormalities observed in obesity using a model lacking leptin. To this purpose, we measured blood pressure in ob/ob and control animals by radiotelemetry combined with fast Fourier transformation before and after both leptin and enalapril treatment. Autonomic function was assessed pharmacologically. Blood pressure during daytime was slightly higher in the ob/ob compared to control mice, while no difference in heart rate was observed. Blood pressure response to trimetaphane and heart rate response to metoprolol were greater in ob/ob mice than in control littermates indicating an activated sympathetic nervous system. Heart rate response to atropine was attenuated. Baroreflex sensitivity and heart rate variability were blunted in ob/ob mice, while low frequency of systolic blood pressure variability was found increased. Chronic leptin replacement reduced blood pressure and reversed the impaired autonomic function observed in ob/ob mice. Inhibition of angiotensin-converting enzyme by enalapril treatment had similar effects, prior to the loss of weight. These findings suggest that the renin-angiotensin system is involved in the autonomic dysfunction caused by the lack of leptin in ob/ob mice and support a role of this interplay in the pathogenesis of obesity, hypertension, and metabolic syndrome.     

新型人工肛门括约肌系统及初步动物实验研究

目的研究可用于治疗肛门失禁的植入式人工肛门括约肌系统（artificial anal sphincter system,AASS）。方法系统由体内执行、体外控制和经皮能量传输3个模块构成,体内外通过无线模式通信。当体内直肠壁上压力超出阈值后,向体外发送排便报警信号,患者通过体外控制模块控制体内执行模块打开或关闭直肠,采用经皮能量传输模块为体内电池充电。通过1例猪的动物实验,评估在活体环境下系统各模块的可靠性和稳定性。15d后将动物解剖,观察组织变化并进行体内的腹泻实验和血供实验。结果植入体内后,体外控制模块可实时控制体内执行模块的各项操作,通过经皮能量传输充电3h,在体内可持续工作24h。拟腹泻状态下,对肠壁施加7．16kPa的压力（正常肛肠静息压为6．26～9．47kPa）,能有效抑制肠道内容物渗漏。结论AASS可以模拟正常人体肛门括约肌功能,为严重肛门失禁的患者提供了一种新的治疗方法。     

Balance between cardiac output and sympathetic nerve activity in resting humans: role in arterial pressure regulation

Large, reproducible interindividual differences exist in resting sympathetic nerve activity among normotensive humans with similar arterial pressures, resulting in a lack of correlation between muscle sympathetic nerve activity (MSNA) and arterial pressure among individuals. Although it is known that the arterial pressure is the main short-term determinant of MSNA in humans via the arterial baroreflex, the lack of correlation among individuals suggests that the level of arterial pressure is not the only important input in regulation of MSNA in humans. We studied the relationship between cardiac output (CO) and baroreflex control of sympathetic activity by measuring MSNA (peroneal microneurography), arterial pressure (arterial catheter), CO (acetylene uptake technique) and heart rate (HR; electrocardiogram) in 17 healthy young men during 20 min of supine rest. Across individuals, MSNA did not correlate with mean or diastolic blood pressure ( r < 0.01 for both), but displayed a significant negative correlation with CO ( r =−0.71, P = 0.001). To assess whether CO is related to arterial baroreflex control of MSNA, we constructed a baroreflex threshold diagram for each individual by plotting the percentage occurrence of a sympathetic burst against diastolic pressure. The mid-point of the diagram ( T ₅₀) at which 50% of cardiac cycles are associated with bursts, was inversely related to CO ( r =−0.75, P < 0.001) and stroke volume (SV) ( r =−0.57, P = 0.015). We conclude that dynamic inputs from CO and SV are important in regulation of baroreflex control of MSNA in healthy, normotensive humans. This results in a balance between CO and sympathetically mediated vasoconstriction that may contribute importantly to normal regulation of arterial pressure in humans.     

Relative stability improves with experience in a dynamic standing task

This study tested the hypothesis that subjects improve their relative stability as they learn a dynamic pulling task. Healthy adult subjects practiced making brief horizontal pulls (<300 ms) on a handle to a range of target forces ranging from 20 to 80% of their estimated maximum for 5 days. They were instructed to always keep their feet flat and begin and end their motion in an upright posture. In order to do this, subjects had to develop the appropriate body momentum prior to the pull and then recover their balance following the pull. We analyzed relative stability during balance recovery, using two measures: spatial safety margin (minimum distance of the center of pressure, COP, to the edges of the feet) and temporal safety margin (minimum extrapolated time for the COP to reach the edges of the feet). We hypothesized that: (1) spatial and temporal safety margins would be uncorrelated; (2) safety-margin means would increase with practice; and (3) safety-margin standard deviations would decrease with practice. Two experiments were conducted: one where subjects practiced three force targets and positioned their initial COP in a small window, and one where subjects practiced two force targets with no initial COP constraint. Results showed that spatial and temporal safety margins were correlated but shared less than 6% variance, indicating that they reflected different aspects of control. Safety-margin averages increased with practice and standard deviations decreased with practice, indicating that the stability of balance control in the execution of this task became more robust. We suggest that the nervous system could use safety margins in both feedback and feedforward control of balance.     

Remote monitoring with automatic hemodialysis system for home hemodialysis

For safe hemodialysis therapy, we developed an automatic blood volume balanced ultrafiltration control system. This system controls the ultrafiltration rate automatically according to changes of blood volume to maintain an adequate blood volume level during hemodialysis. With the use of this system, hypovolemic events were significantly reduced. For the purpose of home hemodialysis, we applied this automatic ultrafiltration rate control system combined with remote monitoring. This system monitors blood pressure, pulse rate, blood volume, oxygen saturation, blood flow rate, ultrafiltration rate, intracircuit pressure, transmembrane pressure, dialysate conductivity, dialysate temperature, anticoagulant infusion, and so on. Furthermore, bidirectional audiovisual information between the patient's bedside console and our hospital was also obtained. All the monitoring data were transmitted with internet system by 64K ISDN cable. This is the first report to confirm the efficacy of an automatic hemodialysis system with remote monitoring in a hemodialysis session of a patient outside the hospital.     

面向家庭健康监护的血压监护模块设计

目的:血压是反映人体循环系统机能的重要生理参数,血压的监测在临床和医疗保健中有着重要的地位。本文根据示波法测量人体血压的原理,研制出了一种面向家庭健康监护的血压监护系统。方法:系统采用s3c2440作为数据采集,传输及气动电路的控制核心,算法部分采用三次样条插值法来获取脉搏波包络线,最终通过幅度系数法求得舒张压和收缩压。结果:通过该系统对人体进行测试,并和柯氏音法进行了对比,得到了比较满意的结果。结论:实验结果显示本系统稳定,可靠,误差率小,可适用于家庭健康监护。